At one time, the biotechs ruled as the market leader, impermeable to low oil prices. But those tides have changed, and Jim Cramer warns that those holdovers could be lurking in your portfolio, ready to cause immense damage.

On Monday the market experienced a dramatic change, when the biotech sector was badly beaten. The change mostly happened on the downfall of Gilead's Hepatitis C monopoly, thanks to Express Scripts selecting competitor AbbVie as its treatment supplier. As a result, Gilead has fallen to $88 from $108 in two days.

It is the umbrella effect of Gilead's beat down that really worries Cramer though. "The notion that the biotechs, as a group, may not have the pricing power we thought they did, and ruinous competition could be lurking around every corner."

So, how much lower can the biotechs go? And when will they once again be safe to own?

The group can be measured by looking at the iShares Nasdaq Biotech ETF, IBB. The ETF has fallen 7 percent in two days, but is still up 29 percent year to date.

"Today's selloff was a shot across the bow for the group, and if the biotech ETF breaks down below $294 and goes any lower, then Fitzpatrick thinks we could have another nasty leg down," added Cramer.

It's not just the biotechs that Cramer is watching. As the averages roar higher, he has watched energy stocks drop furiously. To search for opportunity, Cramer dug through the rubble in the energy space to see if there are any cheap stocks left.

In the past three months, Navigator has fallen more than 40 percent as a result of investor fears of slumping oil prices.

"This is nothing more than lazy, sloppy thinking. The reality is that Navigator Holdings has very little to do with oil prices, but investors get spooked out of the stock because they failed to understand that the value of the company's ships is simply not correlated with energy prices," said the "Mad Money" host.

Ultimately, Navigator's business has no exposure to the price of oil. Cramer thinks this is a cheap stock and could be a great bargain at these prices.

Source: US Air Force

A KC-135 Stratotanker from Fairchild Air Force Base, Wash., refuels a B-1B Lancer during a training exercise Sept. 23, 2014, over South Dakota.

Airline stocks have been roaring recently from low oil prices. That means they will be rolling the dough. Could it also mean that they will invest in upgrading luxury services such as Wi-Fi?

ViaSat is the leading provider of satellite, ground and space systems technology. In particular, it is the satellite broadband provider to airlines such as Jet Blue and United Continental.

Cramer likes this stock, because, in his opinion, this is something that is worth using and competitors provide service that is too slow.

To determine the future of ViaSat, Cramer spoke with CEO Mark Dankberg to find out if the services ViaSat provides could even help with monitoring activity in the Middle East.

"On the fighting in the Middle East and all of the insurgencies there, one of the main support services that we offer is in flight connectivity for aircraft. They can use that for surveillance on the ground and for communications," Dankberg said.

Speaking of the Middle East, Jim Cramer takes one look at the headlines in the news, he knows that days of the U.S. being the global policeman are coming to an end. That doesn't mean defense and aerospace stocks have to break down as well. In fact, they've been roaring lately!

"You see it is happening. The notion of the U.S. being the global policeman is breaking down," Cramer added

The orders for defense equipment overseas are creating an upside that the "Mad Money" host didn't think was possible. Whether it is peace talks with Iran, or pulling out of Afghanistan and Iraq—these are all feeding into the need for countries to become more independent and invest in defense equipment.

"The world is re-arming. We are pretty much the only companies that still make arms in sufficient quantity and size to give you security if you are a threatened regime."

So, despite pullbacks on military spending in the U.S., Cramer thinks the aerospace and defense stocks will break out the big guns in 2015 and keep going higher.